Clay-based hydrogels could be green alternative to polymers

Hydrogels are novel materials with properties unlike those of normal polymers, but their potential applications have remained limited to small niches. A team of researchers from Japan aims to change that, and has discovered a new approach to hydrogels that yielded a trifecta of increased mechanical strength, easy preparation, and possible green-tech implications.

Hydrogels, as the name should imply, are mostly water (as much as 99 percent), and have a consistency that is best described as—you guessed it—a gel. This makes them a great candidate for novel biomedical applications like time-released targeted drug delivery and artificial tissues, because we're mostly water, too. However, this makes them less useful for pretty much everything else outside of the body. They are often vulnerable to solvents and, as you might have noticed, there aren't many items that actively rely on Jell-O as a structural component.

The researchers turned what might be a problem into a solution. The large, branchy dendritic polymer macromolecule they were working with had a tendency to adhere quite strongly to glass. So the researchers investigated its interactions with clay, which shares some properties with glass. Using an additional chemical that disperses clay nanosheets in water, they were able to get their dendritic macromolecule to form a structural framework with the the clay. The hydrophilic portion of the framework attracts and retains water molecules.

This notably improved mechanical properties over other hydrogels, as it could be molded into shapes that are free-standing and relatively robust and would undergo self-healing when cut. Less than 0.4 percent of it is petroleum-derived, so improved versions may provide an appealing green alternative to polymers. The best aspect, however, may be its simplicity: all you need are three ingredients, a beaker of water, and something to stir with.

But since its still a water based material then it can only replace polymer hydrogels

As far as I know, all hydrogels are polymer based in some way (including this one). There's not many other options out there for making the kind of framework you need to trap water like that. The difference between this one and other hydrogels is the mechanical strength, which previous hydrogels lack. So this is basically expanding the envelope of potential uses for hydrogels, not just replacing old ones. Like all materials, if you expand the envelope far enough, you start to impinge on the turf previously held by other materials, which in this case, starts to overlap into soft traditional polymer territory.

Originally posted by ReaderBot:How do you write an entire article about an alternative to polymers without giving any examples of what polymers are used for?

I used to do research on hydrogels for a pharmacuetical company. Crosslinked Polyethylene glycol with lysine in water to create a gel to potentially deliver drugs dissolved in the water. Also a hydrogel that was liquid at room temp. but gelled when injected into the body. Still another gel that was sprayed into the body after surgery to prevent adhesions. After a month, the links would break and the gel would dissolve/be eaten by the body.

There are hydrogel bandaids on the market; been there for years.

When my wife saw the gels I made she too asked about making them into breast implants or using them to deliver cosmetics and skin toners to the face. I wouldn't be surprised if there aren't products like these already on the market.